Fuel feeding device



Oct. 9, 1934. E. A. RocKwELL FUEL FEEDING DEVICE Filed Dec. 24, '1928 4 Sheets-Sheet l 4 Sheets-Sheet 2 iws.

hr1 1. uilww Oct. 9, 1934. E. A. RocKwELL FUEL FEDIG DEVICE Filed Deo. 24, 1928 Oct 9, 1934 E. A. RocKwELL FUEL FEEDING DEVICE Filed Dec. 24, 1928 4 Sheets-Sheet 3 .4 Sheets-Sheet 4 E. A. ROCKWELL FUEL FEEDING DEVI Filed Dec.

Patented @et 9, 1934 iran STATESv PATENT OFFICE FUEL FEEDING DEVICE corporation o! Virginia Application December 24,

1928, Serial No. 328,133

11 claims. (c1. lonas) The purpose of this invention is to provide an improved construction in a pumping device for supplying fuel to an internal combustion engine. The invention consists in the elements and features of construction shown and described as indicated in the claims.

It is a purpose of the present invention to provide a iiexiblediaphragm type of pump which is operable with a variable stroke in accordance with the pressure upon the delivery side ofthe pump by transmitting the impulsive discharge force to the diaphragm through an interposed pressure-limiting spring with means for cutting down the eiective strength of the spring when the diaphragm can only receive a short stroke during the periods of low delivery flow from the pump. For example, if a limiting spring is used having suilicient strength to cause a sufliciently high now at periods-4 of maximum demand, the spring will be too strong at periods of low demand when it receives its maximum compression. Therefore, when the pumping diaphragm is at the limit of its intake stroke, means are provided to frictionally engage' the pump stem opposing the force tending to produce a compression of the limiting spring and movement of the pumping diaphragm. The frictional gripping means is so related tothe return spring which produces the intake stroke of the vpumping diaphragm that at periods of rapid vibration, the return spring will not be allowed suilicient time to return the pumping diaphragm to its full extent into engagement with the frictional gripping means.

Another important purpose of the present invention-resides in the improved construction of the means for supporting the central flexible area of the diaphragm in order to maintain the full effectiveness of the pumping stroke of the diaphragm even when the stroke is very small. Thus it is customary to employ a circular flexible diaphragm as a pumping element which is clamped to the casing at the marginal edge thereof whereby the free area of the diaphragm is 'in excess of the cross sectional area in the plane of the clamped marginal'edge. Rigid disk members'are usually held to opposite sides of the diaphragm in order to render the central portion ofthe diaphragm inflexible but leaving an area of diaphragm material between the clamped central portion and the clamped marginal edge which provides the slack necessary to allow movement of the central iniiexible. portion of the diaphragm. 1

Ii the diaphragm is actuated for a full stroke at all times. the pressure stroke causing discharge from the pumping chamber will produce flexure oi' 'Figure 3.

the slack portion of the diaphragm at the middle of its stroke into an annular depression concave towards the pumping chamber, while the suction stroke will produce a depression of the slack material convex towards the pumping chamber at the middle of its stroke. If, on the other hand, the diaphragm has a variable stroke, it will be obvious that prevented from taking its full stroke the slack portion of the diaphragm will ap from being curved concave to the pumping chamber to be curved convex to the pumping chamber. This napping action will rapidly deteriorate the diaphragm material.

According tothe present invention, means are provided for taking up the slack of the diaphragm V throughout its full stroke which means will prevent the undesirable flapping of the slack material at any position of the stroke.

It is a specic object of the present invention to provide means for taking vrup the slack of the diaphragm which consists of a disk member secured to the diaphragm on the side toward the pumping chamber, which disk member is formed with a marginal annular depression curved convexedly towards the diaphragm and protruding past the 30 clamped inflexible central portion of the diaphragm.

Further objects and advantages will be more clearly apparent and the above-noted improvements will be more fully described in the following detail description taken in connection with the attached drawings.

In the drawingst- Figure 1 is a diagrammatic view for showing the location of the pumping device relatively to 90 the engine and the vehicle, including a main fuel supply tank carried in the customary position at the rear of the vehicle. i

Figure 2 is a top plan view of the pumping device embodying the invention in one of its forms.

Figure 3 is a section at the line 3- 3 on Figure 2.

Figure 4 is a section at the line 4-4 on Figure 2.

Figure 5 is a detail portion of the sectional view of Figure 3 on .an enlarged scale.

Figure is a detail section at the line 6--6 on Figure 2.

Figure 7 is a detail section at the line 'l--7 on Figure 8 is a detail section at the line 8-8 on 105 Figure 6.

Figure 9 is a view looking in thedirection of arrow 9 on Figure 3. I

Figure 10 is a view looking in the directionv of the arrow 10 on Figure 3. 110

` diaphragm.

Figure 16 is a detail section at the line 16-16 on Figure 11.

In the drawings, A represents the engine body of which the crank case is indicated at A1. B is the carbureter of familiar form havinga governed level chamber, B1, in which the level is governed by a oat, B2, and needle valve, B4, and which is connected for fuel discharge to the nozzle, B3. C is the main fuel supply tank located at the rear of the vehicle.

Referring to the form of the invention shown in Figures 2 to 10 inclusive, the pumping device comprises `main housing members, 20 and 30, having faces defined by mated annular flanges, 20 and 30, encompassing recesses, 20h and 30h, in said faces, respectively, for clamping between said flanges a exible diaphragm, 40, which becomes the movable wall of the pumping chamber formed by the recess, 20h, in the casing member, 20. Said casing member, as shown, comprises integrally projecting from the side opposite the diaphragm, 40, at an upper segmental portion thereof, a part, 20x, which has at its under side at a horizontal plane, an annular flange, 21x, within which there is secured an upwardly open cup-shaped filter member, 50, the casing portion, 20x, having an annular seat, 20v, at which said cup-shaped member, 50, makes liquid-tight junction by any convenient securing means. 'I'he passage, 24, leads from the pumping chamber, 20", horizontally into the part, 20x, communicating therein with an upwardly extending passage, 25, which leads through a downwardly projecting boss, 22, which projects and opens at its lower end within the :lter member, 50, whereby it connects with the fuel intake passage with respect to the pumping chamber.

The fuel supply, itv may be understood, is derived from the fuel source shownat C, Figure 1, which under conditions of low supply in the tank or up-grade travel, may require substantial lift of the fuel by suction which the pumping device is adapted to afford, the fuel supply pipe being connected at the entrance to the inlet passage,

51, leading horizontally in from the pipe connection shown at 20 of the casing member, 20x, and downwardly at 51n through the downwardly projecting boss, 52, which extends axially through the filter member, 50, for discharge exteriorly thereof in the sediment and fuel reserve chamber, 20d, formed by a glass bowl, 54, which is clamped and secured in a familiar manner, against the upper marginal flange of the filter member, for holding the latter fluid-tight to the casing as described. The fuel thus reaches the fuel intake passage, 25, onlyv after passing through the filter member.

In the passage, 25, there is placed a bushing, 25, which forms a valve seat for an upwardly opening check valve, 27, which is normally seated by gravity, but is further provided with a coil spring, 83, stopped atits upper end by a screw plug, 60, and at its lower end reacting on the valve, 27, for ensuring its normal seating.

The passage, 24, at the end of its horizontal extent has a part, 24X, which communicates With an upwardly extending passage, 26a, formed in a boss, 65, closed at its upper end by a screw plug, 61, 'and having at its lower part a bushing, 61a, which forms the seat of an upwardly opening check valve, 28, normally seated by gravity, but further provided with a coil spring, 62, stopped at its upper end by the plug, 61I and at its lower end reacting on the valve, 28, for ensuring its normal seating, said spring, 62,5 being stiffer than the spring, 63, which controls the fuel inlet valve, 27, for reasons hereinafter explained.

The vertical passage 26a formed in the boss 65 communicates with a horizontally extending passage 26b formed by a bore through the boss 65 at the lower end thereof and the fuel is thereby delivered into a chamber 23x which will be subsequently described.

To prevent the emptying of the reserve chamber, 20d, and the subsequent passages, which is liable to occur from the leakage of the inlet valve,

27, while the engine is stopped, a vent port is provided at 50h, leading into the passage, 51, which is the crest of the siphon passage leading from the fuel source to said inlet valve.

The boss, 65, with the screw plug, 61, and the `screw plug, 60, aligned with the downwardly projecting boss, 20d, are encompassed by an annular flange, 23, which thus forms a chamber, 23X, which is closed at the top by a pressed metal cap and constitutes a pressure trapping chamber as hereinafter explained. And it will be observed that there is no flow when the carbureter is full so that no fuel can be fed by the feeding ,stroke will be measured by the pressure of the column leading to and comprising the liquid contained in the carbureter reserve chamber.

It is desirable in securing large deliveries of fuel to provide the chamber, 23x, above the inlet valve, 27, (Figure 4) for allowing fuel to be pumped during the high pressure peak of 'the pump as procured by the increasing spring pressure during the impul strokeof the pump. It would sometimes happen that if the trap chamber, 23X, were not there, the spring pressure would increase to a point and then start decreasing beforel the fuel had time to-iow to the carbureter, with the result of a-diminished mean effective pressure and loss of flow. But with the trap chamber, 23X, located as shown, the fuel may be forced into it at the pressure peak, and then during 'the diminishing of the pressure ofthe spring, and also the period of theintake stroke of the pump, the feed of fuel to the carbureter will be maintained by the pressure which has been accumulated in the pressure trapping chamber, 23x. f

Such chambers when arranged above a trap valve generally operate satisfactorilyA for some time, but eventually inelastic liquid fuel absorbing the air Vand vapor will displace the latter, de-l feating the resilient reaction for maintaining the fuel feed to the carbureter. Therefore, during the time of maximum fuel delivery it is necessary to furnish air or produce gaseous vapor to effect what is commonly called scavenging the pressure trap chamber, that is, displacing the liquid which has displaced the-air and vapor and affording the pressure for maintaining uninterrupted feed to the carbureter. To this end in addition to providing the siphon vent, 50, it will be noticed in the drawings, there is a small hole, 50, drilled through from a high point above the strainer into the fuel intake to the strainer chamber.

When the fuel is flowing past this orifice, 50, any vapor formed at the top of the strainer chamber will be sucked in by the flow of the fuel and discharged into the sediment chamber, 50, below the strainer. This action greatly agitates the fuel by this continual circulating process and produces a vapor which assures a lowering of the level of the fuel below the exit, 22, and consequently takes over some of the vapor into the fuel pumping line, said vapor finally accumulating in the trap chamber, 23X, above the outlet valve,vthus producing the desired result of scavenging the fuel which might have otherwise accumulated.

In addition, the vapor generated in this way produces a vacuum in the strainer chamber, 50, when the motor stops, as all of the vapor pressure will be released from above the liquid. This action tends to -completely fill the strainer chamber, and to prime the same. Therefore, even though fuel should be siphoned back to the main supply tank from the carbureter there will always be a quantity of fuel trapped in the pump both in the diaphragm chamber and in the chamber where vapor has been formed. Therefore, this pump becomes self-priming and by the time the trapped fuel is used up, fuel will be drawn in from the supply tank so that at all times the pump will be ready to start on the first turn of the motor.

And it will be understood that beside the function described consisting in equalizing the pressure of the fuel on the 4carbureter, preventing that pressure from pulsating with the back and forth strokes of the diaphragm, the pressure trapped in the chamber, 23X, operates for instantaneous response to the demands of the engine starting after a period of idleness.

The fuel is delivered from the chamber 23x through the pipe F, which is connected to the interiorly threaded bore of the boss 64b extending from the annular flange 23 surrounding the chamber 23x. It will be noted that the opening through the boss 64b is in line with the bored opening 26b formed in the boss 65 in order to permit convenient drilling of the bored opening 26".

The casing member, 30, is extended from the part containing the'recess, 30", having a breather port 30X, obliquely downward in a direction parallel to the planeof the diaphragm, 40, said extension indicated at 30m, terminating in a vertical plane for being mounted upon theoutside of the crank case of the engine, as indicated at 30.

Said casing member is also extended, as'seen at 301, axially with respect to the diaphragm, 40, for affording slide bearing for astem, 100, which is attached to the diaphragm at the center of the latter in a manner hereinafter described, and is telescoped with a plunger, 103, which protrudes from the extension, 30T, and is provided with a disk, 108, secured fixedly on the reduced end of the plunger by a nut, 108, said disk serving for stopping at their outer ends coil springs, 106 and l bers,

107, the outer spring 106 being stopped at its inner end by a shoulder, 30d, formedby counterboring A the casing extension, 30, with certain interposed parts, 104 and 105, hereinafter described, and the.

inner spring 107 being stopped at its inner end by a shoulder, 101, on the stem member. The construction for telescoping connection between the plunger and the stem member is designed, as hereinafter. described, with a view to providing for engagement of the plunger by an actuator at theinner rather than at the outervend `of lthe plunger, as will now be described. The extension, 30m, lof the casing member, 30, is apertured from the end provided for seating on the crank case, as described, to the slide bearing of the stem, 100, in the extension, 30, and the inner end portion of the plunger is transversely apertured for engagement therewith of the end of a lever, 120, which is pivotally supported by an intermediate fulcrum pin 30h, the lever protruding from its fulcrum out through the end, 30, of the casing member which is seated on the crank case wall, for protruding into thecrank case toreceive actuation from the rotating part of the engine indicated in the drawings by a cam, 125, on the shaft, 126, which may be any conveniently accessible shaft for the purpose.

Iii order that the lever at the inner end may reach the aperture of the plunger with which it is to be engaged, as described, and have a range of movement longitudinally of the plunger for actuating the latter, the stem, 100, which, at this portion is telescoped outside -the inner end portion of the plunger, is longitudinally-apertured,` as seen at 100. l

Noting from the foregoing description that the plunger and stem are telescoped with each other, and that the plunger is the inner of the two tele-5 scoped parts, it may be further noted that each of said parts has a portion of its length reduced in diameter, the larger or unreduced portions being telescoped, and the reduced portions protruding at opposite ends, that of the stem protruding for attachment to the diaphragm, and-that of the plunger for carrying the disk on which the springs, 106 and 107, are stopped, as described; and it will be 4noticed that since the reaction of the spring, 107, operates for extending the total assemblage consisting of .the two telescoped memsorne stop means is necessarily provided to limit the extension, and this is provided by the stopping of the plunger head, or unreduced portion, at the Iclosed end of the cavity in the stem in which said head is telescoped.

In this construction it will be seenthat the enlarged portion of the plunger which is telescoped within the larger portion of the stem, is stopped at both ends of its range of telescoping movement, and consequently the parts cannot' be assembled in the relation described without some special provision for admitting 4said larger portion of the plunger into the cavity in which it is reciprocable relatively to the stem. y

The means adopted for this purpose consists in makingl said larger diameter portion of the stem in two parts, the outer part being that to which the reference numeral, 100, is applied, and the inner part of the nature of a bushing, 100x, which is snugly tted within the outer part, being open at the end toward the diaphragm and comprising at the other end the reduced portion, 100, of the stem and the shoulder, 101, for/stopping the spring, said bushing part, 100, being inserted into the open end of the outer member after the plunger has been assembled in said inner bushing nember, 100x, with the reduced end of the plunger telescoped within the reduced portion, 100g, of said inner member of the stem.

For deadening the annoying sound liable to be produced by the stopping of the enlarged portion or head of the plunger at the end of the cavity ofthe enlarged portion of the stem toward which it is thrust by the reaction of the spring, 107, yit is desirable to interpose atthis point a sound-deadening washer, 111, which is made of leather, or like cushioning substance; and this washer is of course put in place in the bottom or outer end of the cavity of the enlarged portion of the inner bushing member, 100x, before the latter is inserted intov the outer main part of said stem, and before the plunger is inserted through said inner bushing member, 100x. d

When the parts are fully assembled in the order indicated, the bushing member, 100x, is made.

securely rigid with the outer main member of the stem by peening over the margin of the end remote from the diaphragmof said outer main stem member onto the shoulder, 101, of the bushing member, which may desirably be peripherally rabbeted, as seen at 100, for accommodating the peened-over margin'.

Between the inner end of the spring, 106, and the shoulder, 30B, of the casing member, 30, which constitutes the stop for the end of said spring, there are interposed, as above mentioned, two parts, viz., a washer, 104, which has at its inner circumference a flange for centering the spring, and between said 'washer and the casing stop shoulder a guide bearing bushing, 105, for the stem, 100. This bushing, hereinafter referred to as the compensating ring, is a somewhat heavy split ring which may be of steel or iron casting having limited resiliency for expanding and contracting in diameter as permitted by its being split, as stated; and theterminal of the enlarged /or unreduced portion of the stem which enters said compensating ring is tapered as seen at 100V, the taper serving to pilot said terminal into the split compensating ring with whose inner circumference it comes into frictional engagement, and wedging thereinto is strong y gripped by the resilient reaction of the ring o setting the reaction of the spring, 107, for giving the diaphragm its feeding stroke.

The purpose of this detail construction will appear upon considering the operation of the `'structure as a whole fox feeding fuel to the carbureter. 'I'his operation will now be described.

Starting with the carbureter reserve chamber empty, upon the engine being operated by the starter, the lever, 120, is acted upon by the cam, 125, in the direction for permitting the retraction of the plunger, 103, in the casing member, 30", with the aid of the spring, 106. In the feeding action the thrust of the plunger is transmitted yieldingly to the stem through the spring, 107, which thus becomes the medium through which the diaphragm is given its feeding movement. The degree to which thev spring, 10'?, iscompressed in the original -assembling of the parts determines the force with which the fuel is fed in the actionof the device; and at starting. with the carbureter reserve chamber andthe pipe leading thereto empty, the spring being conditioned by compression in the assembling approximately to a degree of reaction for upholding a liquid column extending to the high level of the carbureter supply chamber`d and exerting desired pressure on the oat valve therein, will completely transmit to the diaphragm, 40, the thrust of the plunger derived from the lever without the spring itself being further compressed. In the continued operation of the pump the column and pressure are built up to that degree,and afford resistance to the feeding movement of the diaphragm and to the thrust of the stem under the reaction o'f the spring, 107, and said spring yielding to the compression becomes further compressed and conditioned for reaction for giving the diaphragm feeding stroke which is retarded and delayed more or less according to the fuel requirement of the engine, taking fuel delivery from the carbureter supply chamber.

'Ihe spring, 107, is dimensioned for a value of its reaction from the initial compression somewhat in excess of that necessary for meeting the maximum engine requirement of fuel for running at low speed, and for re-action adequate for meeting maximum engine requirement at high speed from the full compression which it will derive from the full stroke of the cam without movement of the diaphragm from fully retracted position reached in the intake stroke.

It maybe understood upon considering the co-operation of the springs, `106 and 107, with the compensating ring, 105, and the tapered terminal, 100", of the diaphragm stem member, 100, as above described, that a, result sought to be accomplished by the construction is to be able to utilize a spring reacting for feeding "stroke of the diaphragm having reaction value adequate for the maximum fuel requirement of the engine and at the same time avoid flooding the carbureter by such strong reaction of the spring under lconditions of low fuel requirement.

And to this end it may be een that the structure may be such that the str ng reaction of the ,feed spring, 107, shall in some manner be oifset under conditions of less than maximum fuel requirement proportionately to the reduction of fuel requirement below the maximum.

Under such conditions of low fuel requirement ysuitable pressure for supplyingthee gine requirement will move the diaphragm o a limited distance in feeding directionaway from the position to which 'it is retracted in the intake stroke, proportionate substantially to the fuel requirement. Accordingly, if the movement of the diaphragm away from fully retracted position is opposed or restrained by means offsetting the spring reaction, so that less than the full reaction of the spring will be operative for for'cing the fuel toward the carbureter, and

if that opposing and offsetting restraint can cor- ,respond to the reduced fuel requirement of the engine, the purpose in View will be accomplished.

Upon considering the construction described, it may be seen that this is the effect of the provision of the compensating ring, 105, co-operating with the tapered terminal of the stem memb'er,.100, which compensating ring. under the conditions of maximum-fuel requirement, will not be in frictional engagement with the tapered terminal of the stem member for a substantial portion of the feeding stroke, because under such conditions the diaphragm will be 'moved to the limit in making its feeding stroke, and the tapered terminal, 100V, will be withdrawn from the 'ring in the verybegwinning of that stroke.

When the engine is running at low speed,

movement than when the engine is running at high speed and creating maximum fuel requirement. Accordingly, the terminal taper ofthe diaphragm stem will be'carried into the compensating ring to the full depth under conditions valve.

of minimum speed and minimum fuel requirement, and more or less approximately to full depth according as the engine speed and the fuel requirement approximate And sin'ce, under conditions of low 4fuel requirement, the pump chamber and discharge passage and carbureter supply chamber are full, and the diaphragm can move only to the extent thatfuel is delivered from the carbureter supply chamber to meet the engine requirement before being halted, by the time the diaphragm will have made this amount of movement under the reaction of the spring, 107, the spring, 106, will have reacted to the full extent, carrying the tapered terminal fully into the compensating ring; and under conditions of low, but not minimum, fuel requirement, the tapered terminal will be carried into the compensating ring a distance proportionate to the engine requirement and speed during the time that the spring, 106, is reacting for retracting the diaphragm. And accordingly the co-operative engagement of the tapered terminalv and the compensating ring will occupy a fraction of the cycle of the pump and engine action corresponding approximately to the degree of reduction and engine speed and fuel requirement below a predetermined maximum at 'which the initial engagement of said co-operating parts occurs.

The reason for having the outlet valve spring, 62, stier than the inlet valve spring, 63, may now be understood. When the delivery rate is cut down, there are periods of increasing and decreasing pressures momentarily in the trap chamber and the fuel line returning to the carbureter needle valve. This is undoubtedly due to a lag in the operation of the float and needle Therefore, whenever the pressure becomes too low on the diaphragm in relation to the tension of the compensating ring and the feed spring, there will be a tendency for the diaphragm to take a greater stroke. The diaphragm stem releases itself from the compensating ring with a result that momentarily a high feed pressure will be produced. In order to avoid this fluctuation and to stabilize this condition, a spring holding the outlet valve can be selected of sufllcient value to sufficiently increase a predetermined minimum pressure in the diaphragm pressure during .the period of the delivery stroke so that the-diaphragm will always have sufficient pressure to prevent it'frfom releasing itself from the compensating ring.

It will be seen, therefore, there is an adaptation of the springs, 106 and 107, to each other and to the compensating or offsetting means, and to the range of fuel requirement ofthe engine and to the extent and `capacity of the fuel supply conduit.

It may be understood that while the drawings show the movable wall of the pumping chamber in the form of a diaphragm, the operation, as above described, is not limited to employment of a diaphragm' as the pumping member.

For certain reasons, however, the diaphragm is preferable to a piston when it is practicable to employ a diaphragm not limited inl respect to its range of movement by its capacity for stretching or reacting from flat to deected form, that is,

when it may be flexed in dimension relatively to the opening which it spans to afford necessary range of movement of the area which is engaged or encountered for the pumping movement.

But with such an amply flexible diaphragm there is encountered the problem of avoiding lo'st motion of the area between the clamped margin and the area to which it is clamped for communieating the movement, that is, of the excess area which permits the movement by virtue of its flexibility only. In the construction shown, this lost motion is prevented and the full value ofthe stroke of the diaphragm for pumping action is obtained by the form of the disks, 41 and 42, between which the diaphragm is clamped at its central area by means of the nut, 100e, on the reduced end of the stem, 100, clamping the parts mentioned against the shoulder. of the stem resulting from the reduction. The disk, 4l, at the side opposite the pumping chamber is radially flexed at the margin so as to present about a curve toward the diaphragm, the central radius of the curve being at an angle of about 45 to the axis, so that the concavely exed annulus first mentioned.

The operation of the diaphragm with the improved form of disks Will now be described. From Figure 14 it.wil1 be noted that at the limit of the intake stroke of the pumping diaphragm the central area of the diaphragm which is infiexibly held between the plane portions of the clamping disks 4l and 42 is substantially in the plane or only slightly beyond the plane of the clamped marginal edge of the diaphragm and at this position all the slack of the diaphragm istaken up due to the form of the disk 42, the annular depression of which extends beyond the plane of the clamped inflexible central area of the diaphragm. Movement of the diaphragm stem in a discharge direction will tend to immediately take up the slack which is yielded, by movement of the diaphragm material, out of contact with theperipheral edge of the disk 42 and therefore the volumetric capacity of the pumping chamber will be decreased exactly in proportion to the stroke of the central iniexible area of the diaphragm as it moves to the position shown in Figure 15. During the oprectlon, a reversal of this action will occur since the disk 42 will take up the slack yielded by movement of the diaphragm. There will, therefore, be no undesirable flapping of the slack portion of the diaphragm which tends to rapidly deteriorate the diaphragm material, the priming time at starting of the pump'is materially reduced and a more constant pressure on the fuel throughout the capacity range is maintained. It AWill be understood that an essential feature of the invention is that when the central inflexible area of the diaphragm is at a position substantially in the plane of the clamped marginal edge that all of the slack material of the diaphragm will be taken up by' conforming to the formation of the disk which is on the side of the diaphragm towards the pumping chamber.

In Figures 11 and 12` there is shown a modified vposite stroke of the diaphragm in an intake diform of the invention in which the plunger derives its positive actuation directly from the cam, 126, on the engine shaft, 125, Without the intervention of a lever as in the structure shown in Figure 3.

In this form the casing member, 300, correspondingto the casing member, 30, of the previously described form, is formed for protruding into the engine crank case, as seen at the reduced terminal,\300a, of said casing member, through rwhich terminal the plunger, 303, extends, and` from which it protrudes for encounter of the cam, 126; and the diaphragmstem, 40Gb, secured at its inner end to the diaphragm 400 in the same manner as the stem in the previously described form, obtains slide bearing in the casing at 30Gb, and is reduced in diameter at the part, 400, outward from said bearing to the end of the stem for telescoping at the end into the plunger, 303, which is axially bored for that purpose and counterbored, as seen at 3031, to accommodate a nut, 400, applied on the reduced and threaded kend of the reduced portion, 4001, for stopping the stem l,relatively to the plunger in the direction of fuel feeding movement of the stem and diaphragm, the plunger being furnished with a terminal wear-button, 401, which closes the outer end of the b ore, 3031, and affords by its inner end the stop for the diaphragm stem, 40011, in said fuel feeding movement. To afford air vent `for the lcavity, 3038, and especially to prevent it from becoming filled with oil and operating as a dash pot in telescoping movement of the diaphragm stem therein, the button is provided with vent and oil grooves, 401, in its outer surface.

To admit oil from the crank case for lubricating the plunger for its stroke in the axial lbore, 300g,

of the casing, an oil port, 300i, is formed in the casing terminal at a point exposed withinl the crank case when the casing is mounted thereon; and to ensure the drainage of the oil back to the crank case and prevent it from being drawn into the diaphragm chamber, from which it would escape through the atmosphere relief or breather port, 300k, said oil port, 30015, is located at the lower side of the casing terminal, 300, as seen in Figure 11.

The spring, 107, encompasses the reduced part,

40Gb, of the stem and reacts between the shoulder 400, resulting from said reduction and the inner end of the plunger; and the spring, 106, reacts between the shoulder, 300e, which results from the counterbore which affords slide bearing for the plunger and the inner end of the plunger.

The operation of this form will be fully understood, without further description, from the description of the operation of the form shown in the previous figures.

In this vform the frictional co-operation between the diaphragm stem and its guide bearing is obtained by the slight taper of the stem at its unreduced portion immediately preceding the reduced portion, and by interposing between a shoulder, 300, and. a flanged washer, 300e, at the end of the spring, 106, a split ring bearing member, 300, identical with the similarly arranged parts of .the preceding figures.

As between the two forms shown respectively' in Figure 3 andFigure 11, the form shown in Figure 3 is preferablyused when the device is to be mounted above or below the cam level, as it affords a. wider range of accommodation to the particular engine which is to be served, in that it is not necessary to mount the casing at a place on the engine directly opposite the engine shaft phragm when used in combination with a substantially vertical fuel receiving and filter trapping chamber takes up less space than possible vwitha construction in which the diaphragm is horizontal with an off-set vertically arranged trapping chamber and, further, -it is still possible to operate the diaphragm by means of .an engineactuated lever which is of an advantage over a construction in which the diaphragm is vertical and the operating stem must protrude into the engine casing, as in the construction of Figures l1 and 12. Furthermore, the inclined arrangement of the diaphragm has the advantage of maintainl ing atrapped supply of fuel in the pumping chamber whereby the pump is always primed and ready to deliver fuel to the carbureter.

Upon considering the construction of the connection through which the pumping member derives movement from the engine cam and the reaction of the springs, in both the forms, shown a casing having a pumping chamber with valvecontrolled inflow and outflow connections to the -pumping chamber, a movable wall operating for expansion and reduction of the pumping chamber and constituting a pumping member, means for operating the movable wall member comprising a plunger actuated positively in a fuel feeding direction, a stem positively attached to the movable wall member, a spring reacting between said positively 'actuated plunger and said stem for transmitting the thrust of the plunger to the stem and thereby to .the movable wall member in the direction of the fuel feeding movement, the spring reacting between the plunger and the stem being initially conditioned for its ultimate reaction approximately corresponding to the pressure of the fuel column extending from the pumping chamber to the carbureter reserve chamber, the casing having a guide bearing for said stem, said bearing and stem being arranged to co-operate frictionally for delaying the movement of the stem and the movable wall at the early part of the positive stroke of the plunger, whereby the' spring is additionally, to a degree corresponding to said delay, conditioned for reaction on the movable Wall member in fuel feeding direction during the latter part of the stroke.

2. A fuel pumping device for supplying fuel to an internal combustion engine which comprises a casing containing a pumping chamber having a' movable wall constituting the pumping member; 15,0

a positively actuated plunger; a stem attached to the movable wall and a spring reacting between said plunger and stem for transmitting yieldingly the thrust of the plunger in the direction for fuel feeding movement of the movable wall, the casing having a guide bearing for the stem, said stem and bearing having parts co-operating for frictionto delay the spring-transmitted movement of the stem and movable wall member in fuel feeding direction, said parts being arranged for their frictional co-operation in the spring-transmitted movement of the movable wall in fuel feeding direction diminishingly as that movement progresses from almost retracted to advanced position of the movable wall.

3. A fuel pumping device for supplying fuel to an internal combustion engine which comprises a casing containing a pumping chamber with a diaphragm forming a moving wall of said chamber and constituting the pumping member, means for operating the diaphragm for pumping comprising a positively actuated plunger, an operating stem of the diaphragm, and a spring by which the thrust of the plunger is transmitted yieldingly to the diaphragm, the casing having a guide bearing forthe stem, said stem and bearing having parts co-operating for friction to delay the spring-transmitted movement of the stem and thereby of the diaphragm upon the thrust of the plunger in fuel feeding direction, said parts being arranged to come into frictional relation in the return of the diaphragm from its feeding movement.

4. An impulse fuel feeding device comprising an impulser and spring-operated means for producing the pumping impulses of the impulser, adapted to act with an effective force decreased at the initial end of its pumping stroke when the delivery rate of the fuel is low.

5. An impulse fuel feeding device comprising an impulser and spring-actuated means for producing the pumping impulses of the impulser, the spring thereof having a force normally in excess of that needed for the maximum feed of fuel and said means having a device for opposing said force at the initial end-of the pumping stroke at low rates of fuel feed.

6. An impulse fuel feeding device comprising an impulser and spring-operated means for producing the pumping impulses of the impulser, the spring thereof having a force normally in excess of that needed for the maximum feed of fuel, and said means having a split ring and tapered collar device for opposing said force at the initial end of the pumping Stroker-at low rates of fuel feed.

7. An impulse fuel feeding device comprising an impulser and spring-operated means nfor producing the pumping movements of the impulser adapted to act with decreased force towards the rearward end of the intake movement when the.

delivery rate of the fuel is low, the spring for said intake movement having a forcenormally in excess of that needed for the maximum fuel intake, but the force of said spring being not sufficiently great to return the impulser to its rearmost position when the fuel is being fed atv a high delivery rate, and sali means having a device for opposing said force at the rearward end of the intake stroke.

8. In a fuel pumping apparatus for supplying fuel to an internal combustion engine, in combination with a pump chamber and a fuel impelling member therein, `-means for actuating said member comprising a spring acting to give it the feeding stroke, and means offsetting the force of the spring in an initial part of the full feeding stroke. A

9. In a pump for supplying fuel to an internal combustion engine, in combination. with a fuel impelling member, and a spring through the force of which said member derives its fuel impelling movement; yielding means for retracting the impelling member for its fuel intake stroke;

-co-operating parts which are respectively carried by the impelling member in its movement and carried in fixed position, adapted to cooperate for offsetting the fuel impelling force of the first mentioned spring; said co-operating parts being relatively formed and positioned for coming into cao-operation for offsetting the first mentioned spring force at the initial part of the movement of the impelling member away from fully retracted position, and for continuing said co-operation for a limited part only of the movement of the impelling member away from that position.

10. In a pumping apparatus for supplying fuel to an internal combustion engine, in combination with a pumping chamber and a fuel impellingv member operating therein for feeding the fuel to the engine; means for actuating said member comprising a spring acting to give it its feeding stroke, and a second spring for retracting it for its intake stroke, the first mentioned spring being of strength and condition for providing a force adequate for supplying the maximum fuel requirement of the engine; means co-operating with a part moving with said fuel impelling member for resisting the feeding impulse to offset the same in part, said co-operating means being positioned and arranged for said co-operation at a limited initial part ofthe feeding movement of said member from fully retracted position, the second mentioned spring being conditioned for reaction compared with the force of the first I spring, s uch as to prevent the full retraction of the fuel impelling member during high delivery rates of the fuel.

11. In a pumping apparatus for supplying fuel to an internal combustion engine, in combination with a pumping chamber, a flexible diaphragm therein constituting the pumping member; means actuating the diaphragm comprising a spring acting to give it yielding feeding stroke, said diaphragm having a stem secured positively thereto at the central part thereof; means carried for movement with said stem, and means co-operating therewith for opposing and retarding the feeding movement of the diaphragm at the initial part of that movement away from'v fully retracted position, and means associated with the diaphragm for preventing slack thereof at the annular area surrounding the securement of the stem thereto.

EDWARD A. ROCKWELL. 

